Normal labour

Question 1

Define labour.

Answer 1

Labour is the process in which the fetus, placenta and membranes are expelled via the birth canal.

Question 2

Normal labour description.

Answer 2

• Spontaneous
• 37-42 weeks gestation
• foetus presenting by the vertex
• Results in a spontaneous vaginal delivery (SVD)

Question 3

What key physiological changes must occur to allow for expulsion of the foetus?

Answer 3

• Cervix softens
• Myometrial tone changes to allow for coordinated contractions
• Progesterone decreases whilst oxytocin and prostaglandins increase to allow for labour to initiate

Question 4

Define stage I of labour.

Answer 4

Time from the onset of labor until complete dilation of the cervix has occurred.

Question 5

Stage I latent phase.

Answer 5

Occurs during onset of labor, ends at 6 cm of cervical dilation. Characterized by mild, infrequent, irregular contractions with gradual change in cervical dilation (< 1 cm per hour).

Question 6

Stage I active phase.

Answer 6

Occurs after the latent phase at ≥ 6 cm of cervical dilation, ends with complete (∼ 10 cm) cervical dilation. Characterized by an increase in the rate of cervical dilation (1–4 cm per hour).

Question 7

Anticipated progress of stage I of labour.

Answer 7

0.5 – 1.0 cm per hour.

Question 8

Definition of stage II of labour.

Answer 8

From full cervical dilatation to the birth of the baby.

Question 9

How long should the active second stage of labour last?

Answer 9

• Primigravida birth would be expected within two hours of active second stage
• Multigravida birth would be expected within one hour of active second stage

Question 10

Definition of stage III of labour.

Answer 10

The time from the birth of the baby to the expulsion of the placenta and membranes.

Question 11

What is prolonged third stage of labour?

Answer 11

If it is not completed within 30 minutes of the birth with active management or within 60 minutes of the birth with physiological management.

Question 12

What does active management of the 3rd stage involve?

Answer 12

• Early clamping and cutting of the umbilical cord (now routine practice is to allow 2-5 minutes of delayed cord clamping for all women unless contraindicated)
• Use of uterotonic medications
• Delivery of the placenta by controlled cord traction

Question 13

Which drugs does the active management of the 3rd stage use?

Answer 13

• Syntometrine
• Oxytocin

Question 14

Progress and monitoring

Answer 14

• Maternal observations
• Abdominal palpation
• Vaginal examination
• Monitoring of liquor
• Auscultation of the fetal heart
• Palpation of uterine muscle contractions

Question 15

Mechanism of labour

Answer 15

• Descent
• Flexion
• Internal rotation of the head
• Crowning and extension of the head
• Restitution
• Internal rotation of the shoulders
• External rotation of the head
• Lateral flexion

Question 16

Non pharmacological analgesia.

Answer 16

• breathing exercises
• aromatherapy
• water
• hyponobaby
• TENS machine

Question 17

Simple analgesia

Answer 17

• paracetamol
• dihydocodeine
• aspirin

Question 18

Other analgesia

Answer 18

• Entonox - nitrous oxide
• opiates
• epidural
• spinal anaesthesia

Question 19

Paracetamol

Answer 19

Safe throughout pregnancy; may be used in latent phase of labour for pain relief

Question 20

Dihydrocodiene

Answer 20

• May be useful in latent phase of labour
• Make sure patient aware of side effects (nausea, constipation, drowsiness)
• Risk of neonatal respiratory depression

Question 21

Aspirin

Answer 21

Avoid in labour for acute pain relief as it increases bleeding risk

Question 22

Risks from taking NSAIDs in pregnancy

Answer 22

• premature closure of the foetal ductus arteriosus
• foetal oliguria
• oligohydramnios after 30 weeks gestation
• bleeding in foetus

Question 23

Entonox

Answer 23

• Patient can self-administer during contractions by inhaling through a mouthpiece attached to the wall
• Quick onset, short half-life
• Usually reserved until in active labour

Question 24

Opiates

Answer 24

• Can cause nausea and vomiting, drowsiness and respiratory depression in the woman
• Can cause neonatal respiratory depression
• Usually co-prescribe with an antiemetic
• example is Remifentanyl PCA (Patient controlled analgesia)

Question 25

Antidote to opiate

Answer 25

Naloxone

Question 26

When is local anaesthetic used?

Answer 26

* injected intradermally before a woman has a large bore IV cannula inserted * used after delivery to suture an episiotomy or vaginal tear * pudendal nerve block before an assisted/instrumental vaginal delivery

Question 27

What drug is normally used for a local anaesthetic?

Answer 27

Lidocaine

Question 28

Epidural

Answer 28

* Woman and fetus require monitoring when epidural in situ; labour must be managed on a labour ward * Epidurals are sited by an anaesthetist * Involves injection of local anaesthetic and opiate medications into the epidural space using a catheter

Question 29

Epidural advantages

Answer 29

* Effective analgesia during labour * Can be topped up if need to transfer to theatre for instrumental or caesarean section delivery * Effective after delivery if need to repair vaginal tears or manual removal of placenta (MROP) * Best for baby * Can prevent further raised blood pressure in pre-eclampsia

Question 30

Epidural disadvantages

Answer 30

* Can fail to provide adequate analgesia (1 in 10 need re-sited) * Causes hypotension (1 in 50 chance; dose-dependent) * Reduces woman’s mobility * Dural puncture (1 in 100 chance) * Epidural haematoma / abscess (\<1 in 10000 chance) * Risk of respiratory depression (1 in 100 to 1 in 1000 chance) * Risk of neurological deficits (1 in 10000 to 1 in 40000 chance)

Question 31

Spinal anaesthesia

Answer 31

* Used for most caesarean sections (elective and emergency) * Usually a local anaesthetic and opiate medication are injected into the subarachnoid space * The anaesthetist must check the level of the anaesthetic block is adequate before the operation begins

Question 32

Spinal anaesthesia advantages

Answer 32

* Gives dense, anaesthetic bilateral block * Patient can stay awake & protect own airway during operation * woman can stay awake to meet her baby

Question 33

Spinal anaesthesia disadvantages

Answer 33

* 2-3% risk of inadequate pain relief - may need other analgesics or may require general anaesthetic * Shorter duration - can wear off. May be problem if surgery takes longer than expected (\>60-90mins) * Causes hypotension (due to blockade of the sympathetic nerves) similar to epidural and general anaesthetic * Patient needs urinary catheter * Risk of dural puncture - post dural puncture headache * Patient may suffer from pruritus or nausea and vomiting * Small risk of nerve damage

Question 34

Dural puncture

Answer 34

* post dural puncture headache (worse on sitting up or standing; can be treated using a epidural blood patch)

Question 35

When may a general anaesthetic be required for a pregnant woman and what are the risks?

Answer 35

* General anaesthetic (GA) agents may be required for pregnant women for example if an emergency caesarean section is needed and there is not enough time to site a spinal anaesthetic block or if spinal anaesthesia fails * General anaesthesia can be more difficult in pregnancy due to increased risk of aspiration of stomach contents and more difficult intubation in pregnant women